ORGANIC CHEMISTRY 7TH EDITION BY BROWN – TEST BANK
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Sample Test
CHAPTER 3—STEREOISOMERISM AND CHIRALITY
MULTIPLE CHOICE
1. Which
of the following is the definition of a pair of enantiomers?
|
a. |
A pair of structures that
are superposable mirror images of one another |
|
b. |
A pair of stereoisomers
that are non-superposable mirror images of one another |
|
c. |
A pair of stereoisomers
that are not mirror images of one another |
|
d. |
A pair of stereoisomers
that have equal specific rotations |
ANS: B
2. Which
of the following is the definition of a pair of diastereomers?
|
a. |
A pair of structures that
are superposable mirror images of one another |
|
b. |
A pair of stereoisomers
that are non-superposable mirror images of one another |
|
c. |
A pair of stereoisomers
that are not mirror images of one another |
|
d. |
A pair of stereoisomers
that have equal specific rotations |
ANS: C
3. Which
of the following is the definition of chirality?
|
a. |
The non-superposability of
an object on its mirror image |
|
b. |
The superposability of an
object on its mirror image |
|
c. |
A molecule that has a
carbon atom with four different substituents |
|
d. |
A molecule with a mirror
image |
ANS: A
4. Which
of the following is the definition of a meso compound?
|
a. |
A molecule with
stereocenter centers which is chiral |
|
b. |
A molecule with
stereocenter centers which is not chiral |
|
c. |
A diastereomer with no
stereocenter centers |
|
d. |
A chiral compound with more
than one stereocenter center |
ANS: B
5. Which
of the following statements is not true
regarding pairs of enantiomers?
|
a. |
They have identical melting
points |
|
b. |
They have identical boiling
points. |
|
c. |
They rotate plane polarized
light in opposite directions |
|
d. |
They react at identical
rates with chiral reagents |
ANS: D
6. Which
of the following statements is true?
|
a. |
All mirror images are
enantiomers |
|
b. |
All molecules that have
stereocenter centers are chiral |
|
c. |
Isomers that are not
superposable on their mirror images are enantiomers |
|
d. |
Superposable structural
isomers are enantiomers |
ANS: C
7. Which
of the following structures is different from the other three?
|
a. |
1 |
|
b. |
2 |
|
c. |
3 |
|
d. |
4 |
ANS: D
8. Which
of the following structures is different from the other three?
|
a. |
1 |
|
b. |
2 |
|
c. |
3 |
|
d. |
4 |
ANS: C
9. Which
of the following compounds is/are chiral?
|
a. |
only 1 |
|
b. |
only 1 and 2 |
|
c. |
only 2 and 3 |
|
d. |
1, 2 and 3 |
ANS: A
10. Which
of the following compounds is/are chiral?
|
a. |
only 1 |
|
b. |
only 1 and 2 |
|
c. |
only 2 and 3 |
|
d. |
1, 2 and 3 |
ANS: A
11. Which
of the following have the S configuration?
|
a. |
only 1 |
|
b. |
only 2 |
|
c. |
only 1 and 2 |
|
d. |
1, 2 and 3 |
ANS: C
12. Which
of the following have the R configuration?
|
a. |
only 1 |
|
b. |
only 2 |
|
c. |
only 1 and 2 |
|
d. |
1, 2 and 3 |
ANS: D
13. What
is the configuration of the two chiral centers in the following molecule?
|
a. |
3R,5R |
|
b. |
3R,5S |
|
c. |
3S,5R |
|
d. |
3S,5S |
ANS: B
14. What
is the configuration of the two chiral centers in the following molecule?
|
a. |
3R,5R |
|
b. |
3R,5S |
|
c. |
3S,5R |
|
d. |
3S,5S |
ANS: C
15. Which
of the following Newman projections represents (2R,3R)-dibromobutane?
|
a. |
1 |
|
b. |
2 |
|
c. |
3 |
|
d. |
4 |
ANS: A
16. Which
of the following Newman projections represents meso-2,3-dibromobutane?
|
a. |
1 |
|
b. |
2 |
|
c. |
3 |
|
d. |
4 |
ANS: C
17. Which
of the following structures represent the same stereoisomer?
|
a. |
only 1 and 2 |
|
b. |
only 1 and 3 |
|
c. |
only 2 and 3 |
|
d. |
1, 2 and 3 |
ANS: C
18. Which
of the following structures represent the same stereoisomer?
|
a. |
only 1 and 2 |
|
b. |
only 1 and 3 |
|
c. |
only 2 and 3 |
|
d. |
1, 2 and 3 |
ANS: C
19. Which
of the following structures represent the same stereoisomer?
|
a. |
only 1 and 2 |
|
b. |
only 1 and 3 |
|
c. |
only 2 and 3 |
|
d. |
1, 2 and 3 |
ANS: A
20. Which
of the following compounds is a meso compound?
|
a. |
(2R,3R)-dibromobutane |
|
b. |
(2R,3S)-dibromobutane |
|
c. |
(2R,3S)-3-bromo-2-butanol |
|
d. |
(2R,3R)-3-bromo-2-butanol |
ANS: B
21. How
many stereoisomers of 2,3-dimethylbutane, (CH3)2CHCH(CH3)2,
exist?
|
a. |
1 |
|
b. |
2 |
|
c. |
3 |
|
d. |
4 |
ANS: A
22. How many
stereoisomers of 3-chloro-2-methylbutane, (CH3)2CHCHClCH3,
exist?
|
a. |
1 |
|
b. |
2 |
|
c. |
3 |
|
d. |
4 |
ANS: B
23. How
many stereoisomers of 3-bromo-2-butanol, CH3CH(OH)CHBrCH3,
exist?
|
a. |
1 |
|
b. |
2 |
|
c. |
3 |
|
d. |
4 |
ANS: D
24. How
many stereoisomers of 2,3-butanediol, CH3CH(OH)CH(OH)CH3,
exist?
|
a. |
1 |
|
b. |
2 |
|
c. |
3 |
|
d. |
4 |
ANS: C
25. How
many stereoisomers of 2,4-dimethylpentane, (CH3)2CHCH2CH(CH3)2,
exist?
|
a. |
1 |
|
b. |
2 |
|
c. |
3 |
|
d. |
4 |
ANS: A
26. How
many stereoisomers of 4-chloro-2-methylpentane (CH3)2CHCH2CHClCH3,
exist?
|
a. |
1 |
|
b. |
2 |
|
c. |
3 |
|
d. |
4 |
ANS: B
27. How
many stereoisomers of 4-bromo-2-pentanol, CH3CH(OH)CH2CHBrCH3,
exist?
|
a. |
1 |
|
b. |
2 |
|
c. |
3 |
|
d. |
4 |
ANS: D
28. How
many stereoisomers of 2,4-pentanediol, CH3CH(OH)CH2CH(OH)CH3,
exist?
|
a. |
1 |
|
b. |
2 |
|
c. |
3 |
|
d. |
4 |
ANS: C
29. How
many isomers (constitutional and stereoisomers) exist for dimethylcyclobutane?
|
a. |
3 |
|
b. |
4 |
|
c. |
5 |
|
d. |
6 |
ANS: D
30. How
many isomers (constitutional and stereoisomers) exist for dimethylcyclohexane?
|
a. |
3 |
|
b. |
5 |
|
c. |
6 |
|
d. |
9 |
ANS: D
31. How
many isomers (constitutional and stereoisomers) exist for dimethylcyclopentane?
|
a. |
3 |
|
b. |
5 |
|
c. |
7 |
|
d. |
9 |
ANS: C
32. How
many isomers (constitutional and stereoisomers) exist for dimethylpentane?
|
a. |
2 |
|
b. |
3 |
|
c. |
4 |
|
d. |
5 |
ANS: C
33. Which
of the following statements regarding optical rotation is not true?
|
a. |
All (+) enantiomers are
dextrorotatory. |
|
b. |
All R enantiomers
are dextrorotatory. |
|
c. |
All (-) enantiomers rotate
plane-polarized light in a counterclockwise direction. |
|
d. |
All (+) and (-) enantiomers
rotate plane-polarized light in opposite directions. |
ANS: B
34. How
much of the R enantiomer
is present in 10 g of a mixture which has an enantiomeric excess of 20% of the S isomer?
|
a. |
1 g |
|
b. |
2 g |
|
c. |
4 g |
|
d. |
6 g |
ANS: C
35. How
much of the R enantiomer
is present in 10 g of a mixture which has an enantiomeric excess of 60% of the R isomer?
|
a. |
2 g |
|
b. |
4 g |
|
c. |
6 g |
|
d. |
8 g |
ANS: D
36. A
solution containing 0.2 g/mL of a pure R enantiomer
in a 1 dm polarimeter rotates plane polarized light by +3°. What is the
specific rotation of the R isomer?
|
a. |
+0.6° |
|
b. |
+15° |
|
c. |
+67° |
|
d. |
+150° |
ANS: B
37. A
solution containing 0.04 g/mL of a pure S enantiomer
in a 1 dm polarimeter rotates plane polarized light by +2°. What is the
specific rotation of the R isomer?
|
a. |
-50° |
|
b. |
-20° |
|
c. |
+10° |
|
d. |
+50° |
ANS: A
38. A
solution containing 0.2 g/mL of a pure R enantiomer
in a 1 dm polarimeter rotates plane polarized light by +2.8°. What is the
rotation of a solution containing 0.4 g/mL of the R isomer in the same
polarimeter?
|
a. |
+0.7° |
|
b. |
+1.4° |
|
c. |
+2.8° |
|
d. |
+5.6° |
ANS: D
39. A
solution of 0.1 g/mL of a pure R enantiomer
in a 1 dm polarimeter rotates plane polarized light by +4.8°. What is the
rotation observed on this solution in a 2 dm polarimeter?
|
a. |
+2.4° |
|
b. |
+4.8° |
|
c. |
+9.6° |
|
d. |
+19.2° |
ANS: C
40. A
pure sample of the R enantiomer
of a compound has a specific rotation, [a], of +20°. A solution containing 0.2
g/mL of a mixture of enantiomers rotates plane polarized light by -2° in a 1 dm
polarimeter. What is the enantiomeric excess (%ee) of the mixture?
|
a. |
25% R |
|
b. |
40% S |
|
c. |
50% S |
|
d. |
70% R |
ANS: C
41. A
pure sample of the R enantiomer
of a compound has a specific rotation, [a], of -15°. A solution containing 0.6
g/mL of a mixture of enantiomers rotates plane polarized light by -3° in a 1 dm
polarimeter. What is the enantiomeric excess (%ee) of the mixture?
|
a. |
33% R |
|
b. |
33% S |
|
c. |
50% R |
|
d. |
75% R |
ANS: A
42. Which
of the following structures has a center of symmetry?
|
a. |
1 |
|
b. |
2 |
|
c. |
3 |
|
d. |
4 |
ANS: C
43. Which
of the following structures has a center of symmetry (i.e., center of inversion)?
|
a. |
1 |
|
b. |
2 |
|
c. |
3 |
|
d. |
4 |
ANS: C
44. Which
of the following structures have a plane of symmetry?
|
a. |
only 1 and 2 |
|
b. |
only 2 and 4 |
|
c. |
only 3 and 4 |
|
d. |
1, 2, 3 and 4 |
ANS: C
45. Which
of the following structures does not have
a plane of symmetry?
|
a. |
only 2 |
|
b. |
only 1 and 2 |
|
c. |
only 3 and 4 |
|
d. |
only 1, 2 and 4 |
ANS: A
46. How
many chiral centers are there in the following molecule (the naturally
occurring stereoisomer is the male hormone testosterone)?
|
a. |
Three |
|
b. |
Four |
|
c. |
Six |
|
d. |
Seven |
ANS: C
47. How
many chiral centers are there in the following molecule (the naturally
occurring stereoisomer is camphor, a pungent moth repellent)?
|
a. |
Two |
|
b. |
Three |
|
c. |
Four |
|
d. |
Five |
ANS: A
48. Which
of the following is the best definition of a pair of atropisomers?
|
a. |
A pair of enantiomers which
do not interconvert. |
|
b. |
A pair of enantiomers which
lack chiral centers. |
|
c. |
A pair of enantiomeric
structures which lack chiral centers and interconvert by rotation around
carbon-carbon single bonds. |
|
d. |
A pair of enantiomers which
lack chiral centers and do not interconvert because of hindered rotation
around carbon-carbon single bonds. |
ANS: D
49. Which
of the following structures is chiral?
|
a. |
1 |
|
b. |
2 |
|
c. |
3 |
|
d. |
4 |
ANS: C
50. Which
of the following substituents has the highest priority according to the
Cahn-Ingold-Prelog system used in assigning R and S configurations?
|
a. |
-COOH |
|
b. |
-CHO |
|
c. |
-CH2OH |
|
d. |
-CH3 |
ANS: A
51. Which
of the following substituents has the highest priority according to the
Cahn-Ingold-Prelog system used in assigning R and S configurations?
|
a. |
-NH2 |
|
b. |
-NHCH3 |
|
c. |
-CH2NH2 |
|
d. |
-CH2NHCH3 |
ANS: B
52. What
is the correct order of the Cahn-Ingold-Prelog ranking of the following
substituents as used in assigning R and S configurations of
chiral centers? (higher ranking > lower ranking)
|
1. |
-CºCH |
2. |
-CH2NH2 |
3. |
-NHCH3 |
4. |
-CN |
|
a. |
3 > 4 > 2 > 1 |
|
b. |
4 > 3 > 1 > 2 |
|
c. |
3 > 4 > 2 > 1 |
|
d. |
4 > 3 > 2 > 1 |
ANS: C
53. What
is the correct order of the Cahn-Ingold-Prelog ranking of the following
substituents as used in assigning R and S configurations of
chiral centers? (higher ranking > lower ranking)
|
1. |
-CH2OH |
2. |
-CHO |
3. |
-OCH3 |
4. |
-OCOCH3 |
|
a. |
3 > 4 > 1 > 2 |
|
b. |
4 > 3 > 1 > 2 |
|
c. |
3 > 4 > 2 > 1 |
|
d. |
4 > 3 > 2 > 1 |
ANS: D
54. What
is the relationship between the following pair of structures?
|
a. |
They are enantiomers |
|
b. |
They are diastereomers |
|
c. |
The are constitutional
isomers |
|
d. |
They are identical |
ANS: D
55. What
is the relationship between the following pair of structures?
|
a. |
They are enantiomers |
|
b. |
They are diastereomers |
|
c. |
The are constitutional
isomers |
|
d. |
They are identical |
ANS: B
56. What
is the relationship between the following pair of structures?
|
a. |
They are enantiomers |
|
b. |
They are diastereomers |
|
c. |
The are constitutional
isomers |
|
d. |
They are identical |
ANS: A
TRUE/FALSE
1. Of
the compounds listed below, only 2 has a chiral centers.
ANS: T
2. An
unknown sample is tested with a polarimeter for optical activity. The
results of the test required no movement of the analyzer.
This sample could be either a meso compound or a racemic mixture.
ANS: T
3. The specific
rotation of enantiomers have the same magnitude.
ANS: T
4. The
terms that best describe the relationship between (2R,3S)-2,3-butanediol
and (2S,3S)-2,3-butanediol are
configurational and diastereomers.
ANS: T
5. Of
the following molecules, both 1 and 2 have a mirror plane of symmetry.
ANS: F
6. The
following two compounds represent a pair of enantiomers.
ANS: F
7. A
natural product having [a]D =
+40.3° has been isolated and purified. This indicates that the
natural product is dextrorotatory.
ANS: T
8. A
natural product having [a]D =
+40.3° has been isolated and purified. Either of the following
substances could be this natural product.
ANS: F
9. A
work glove is chiral but disposable surgical gloves are not.
ANS: T
10. In
muscle tissue only (+)-lactic acid is found but in sour milk both (+)-lactic
acid and (-)-lactic acid are present. This difference might be explained
by the fact that the production of lactic acid in muscle tissue is catalyzed by
biological catalysts or enzymes.
ANS: T
COMPLETION
1. The
process that separates enantiomers is called ______________.
ANS: resolution
2. A
mixture containing 0.50 mmol of each enantiomer is called a ___________mixture.
ANS: racemic
3. For
the compound shown below the number of chiral stereoisomers that can be drawn
is_____.
CH3CHClCHBrCH3
ANS:
4
four
4. The
number of chiral centers in progesterone (shown below) is ______.
ANS: 6
six
5. The
following structures depicts (__)-3-ethyl-2,3-dimethylhexane.
ANS:
R R
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